RT @agshapiro2@twitter.com
The perptual diamond: The diamond remains fixed in one place but appears to move up, down, left, or, right. See how far away you can be from your screen before the effect goes away. From https://journals.sagepub.com/doi/full/10.1177/2041669518815708
??: https://twitter.com/agshapiro2/status/1135286867182706688